Fort Jefferson - Dry Tortugas National Park, Florida

Address:Garden Key, Florida

Fort Jefferson - This huge fort is located in Dry Tortugas National Park, about 70 miles west of Key West, and is only accessible by boat or seaplane. The largest brick fort in the U.S., Fort Jefferson was constructed from 1845-1875, but never fully completed. It was designed to hold 1,500 troops and 450 cannons. The only war "action" this fort saw was when the Union army took it from the Confederates (Florida was part of the Confederacy) in the U.S. Civil War.